The present invention is related to optical sensors disposed within a surface over which vehicles are driven, which are exposed to environmental conditions, and in particular, to methods and apparatus for protecting optical surfaces from environmental debris and for the automatic clearing of accumulated environmental debris from the optical surfaces.
The use of optical sensors for the acquisition of data associated with motor vehicle are becoming prevalent in the automotive service industry and for use in monitoring vehicular traffic. For some applications, such as the acquisition of data associated with vehicle wheels, and in particular, tire conditions, the optical sensors are disposed in, or below, a supporting surface over which the vehicle wheels roll, such as a roadway surface, vehicle service bay floor, or vehicle service/inspection support structure. Embedded or drive-over optical sensors may include components for projecting illuminating energy towards and onto the surfaces of a passing vehicle, as well as receiving components for capturing reflected energy from the passing vehicle. For example, some tire tread depth measurement systems consist of a laser emitter configured to project a laser light onto or across the surface of a tire passing over the optical sensor, and a cooperatively configured imaging sensor disposed in proximity for acquiring images of the projected laser light reflected from the passing tire.
Optical sensors disposed in a drive-over configuration, where a vehicle is driven or rolled over the sensor, are typically contained within a sealed housing having one or more panels of optically transparent material such as glass or plastic through with illuminating light is projected and/or reflected light is observed. While such sealed housings function well to provide protection against water or debris intrusion and damage to the sensors, performance of the sensors can be degraded to the point of inoperability by the accumulation of environmental contaminants, such as dust, dirt, rocks, salt, and water on the optically transparent panels. Such accumulations of environmental contaminates can occlude the optical lines of sight for both emitter components and imaging components.
Accordingly, it would be advantageous to provide optical sensors, disposed in a drive-over configuration, with components for preventing or impeding environmental contaminates from falling onto the panels of optically transparent material and adjacent sensor surfaces. The mechanisms may be either active mechanisms, in the form of movable shields, guards, or deflectors, or passive components such as drip edges, water-accumulating textured surfaces, flow diverters, or selectively placed flanges or fixed guards.
It would be further advantageous to provide optical sensors, disposed in a drive-over configuration, with a mechanism for selectively shielding the panels of optically transparent material during periods of inactivity. In one embodiment, the shielding mechanism is recessed below the surface over which a vehicle is driven in order to isolate the shielding mechanism from direct contact with the vehicle wheels.
It would be further advantageous to provide optical sensors, disposed in a drive-over configuration, with a mechanism for cleaning and/or clearing of environmental contaminates from the exposed surface of the panels of optically transparent material and adjacent surfaces.